Traditional keyboards, such as the QWERTY and the DVORAK keyboards, have been designed as keyboard for typing with ten fingers. Typically, proficient typists will orient their fingers on the so-called "home" keys (on the QWERTY keyboard, the keys "asdf" for the left hand and "jkl;" for the right hand) and typing letters will either be on this home row or involve a move to some adjacent keys, one row below the home row, or one or two rows above. Consequently, there is little significant finger travel and the typist maintains an orientation on the "home" keys.
U.S. Pat. Nos. 5,352,050, 4,244,659, 4,655,621, 3,970,185, 2,080,457, and 2,040,248, optimize the layouts of ten-finger keyboards based on the frequency of usage of the letters in a target language. These patents, however, are optimized for the use of ten-finger keyboards and do not result in any significant reduction of travel for a single finger or electronic pen user. Other keyboards, such as U.S. Pat. No. 5,336,002, have been optimized for use with multiple fingers on a single hand.
The situation is quite different on a pen computer or a computer utilizing a touch screen and also on miniature keyboards found in many personal digital assistants. In these situations, input is performed with a single finger, or with an electronic pen or some equivalent device. The same finger, or other input device, must travel to successive keys one by one which requires considerable finger (or pen) travel.
Clearly, the adoption of the QWERTY layout, or other layouts optimized for multiple finger input, for such on-screen keyboards is very inefficient and is only the outcome of an extrapolation of such keyboards to a context where the premisses are quite different. In addition to the issue of pen travel, there is the additional fact that an on-screen keyboard will always require that a user look at the keys on the keyboard which is unlike the practice of touch-typists on a ten-finger keyboard. The ten-finger knowledge of a keyboard does not translate necessarily into a knowledge of where to look for each consecutive key, and this observation has sometimes led to the adoption of a purely alphabetical keyboard for certain systems. However, alphabetical keyboards do not result in lesser pen or finger travel.